The groups say that until Chase made changes to the contest, they appeared to be among the top 100 vote-getters.

“They never gave us any indication that there was any problem with our organization qualifying,” said Micah Daigle, executive director of Students for Sensible Drug Policy. “Now they’re completely stonewalling me.”

“This is a problem of accountability,” said David Lee, executive director of Justice for All. “Simply publish the votes and let us see that the 100 organizations named as winners won.”

Contests using social media to award or raise money for charities have exploded, as companies and nonprofit groups test the use of Facebook, Twitter and other online tools for marketing and fund-raising.

The Chase Community Giving contest is one of the largest ever mounted, open to more than a half-million charities. More than a million people signed onto Chase’s fan page, where they were awarded 20 votes to cast for the charities of their choice.

In an e-mail message to Mr. Lee, Joseph Evangelisti, a spokesman for Chase, explained the thinking behind the changes in the contest.

“Regarding the vote tallies,” Mr. Evangelisti wrote, “we have taken down individual charity counts with a couple of days left to build excitement among the broadest number of participants, as well as to ensure that all Facebook users learn of the 100 finalists at the same time and so we have an opportunity to notify the 100 finalists first.”

In a telephone interview, Mr. Evangelisti declined to give the vote tallies for any of the organizations or to say whether any of the groups that are complaining had been disqualified. Chase’s eligibility rules make it clear that the bank can disqualify any participant.

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“We are proud that through this effort we’re giving $5 million to small and local charities,” he said, “raising awareness for thousands of charities and helping them gain new supporters.”

In such contests, companies typically select a group of charities and ask people to vote for one of them. But Chase opened its contest to any charity whose operating budget was less than $10 million and whose mission “aligned” with the bank’s corporate social responsibility guidelines. Organizations also had to affirm that they did not discriminate in any way.

Chase did not create a public leader board showing a ranking of the charities based on the votes they had received on its Chase Community Giving page on Facebook. Instead, participating charities had to go to Facebook to find out how many votes they had received and who had voted for them.

So some participants created informal leader boards. For instance, the National Youth Rights Association, a tiny nonprofit that works to teach young people about their rights and how to protect them, compiled voting data on almost 400 contestants, and 82 of the organizations that it tracked were among the 100 winners Chase named.

The association itself was among those winners, and the $25,000 it will get from Chase is more money than it has raised all year and the largest donation it has received in its 11-year history, said Alex Koroknay-Palicz, its executive director.

“For the most part, the organizations Chase picked were exactly the organizations we expected to win, because we had spent a lot of time and effort tracking it,” Mr. Koroknay-Palicz said. “So the biggest surprise was Students and a couple of pro-life groups, as well as the organization called the Prem Rawat Foundation, didn’t make it, because they had been doing pretty well.”

According to the leader board he created, Students for Sensible Drug Policy collected 2,305 votes through Dec. 9, when organizations no longer could track their votes or see who had voted for them. The Marijuana Policy Project had 1,911 votes, and Justice for All had 1,512.

The Prem Rawat Foundation, a humanitarian group, had 4,324 votes. It did not respond to a message left at its offices. Mr. Evangelisti said the 100 finalists “reflect those organizations that received the most votes among eligible participants.”

Mr. Lee, a veteran of these types of contests, said the changes Chase made on Dec. 9 had made it much more difficult to continue attracting votes. After the changes, would-be supporters of Justice for All called and e-mailed to say they could not get their votes to go through.

A version of this article appears in print on December 19, 2009, on Page A13 of the New York edition with the headline: Charities Criticize Online Fund-Raising Contest by Chase. Order Reprints|Today's Paper|Subscribe